Anti-hum device



June 30, 1959 R. w. ERIKSQN ANTI-HUM DEVICE Filed Oct. 25, 1955 2 Shae ts-Sheet 1 INVENTOR ROBERT W. ERIKSON ATTORN EYS FIG. 2

R. w. ERIKSON ANTI-HUM DEVICE June 30, 1959 2 Sheets-Sheet 2 Filed Oct. 25, 1955 INVENTOR ROBERT W. ERIKSON B 1M, 17 EMA, l w

ATTORNEYS United States Patent ANTI-HUM DEVICE Robert W. Erikson, Rockford, Ill., assignor to Sundstrand Machine Tool Co., an Illinois corporation "Application October 25, 1955, Serial No. 542,699

Claims. (Cl. 103-4) pumping mechanism so as to prevent the transmission of objectionable noise to other structures.

' Another object is to provide a pumping mechanism of the character described having a new and improved antihum device including a body of resilient, shock absorbent material positioned in the pumping chamber so as to be substiantially immersed in the fluid to absorb vibrations transmitted to the fluid from the pumping mechanism.

A further object is to provide a fluid pumping device of the type described having a cylindrically shaped screen encircling the pumping mechanism in the pumping chamber to filter the fluid delivered to the pumping mechanism, an annular body of resilient material positioned in the pumping chamber to absorb pulsations transmitted to the fluid from the pumping mechanism, an annular rim for supporting the annular body, an annular clamping member for holding the screen and rim, and a removable end plate forming a part of the casing for the pumping mechanism removably retaining the clamping member in position in the pumping chamber.

It is also an object of the invention to provide a hydraulic pumping device of the type described in the preceding paragraph, including a lift pump for drawing fluid into the reservoir, 2. piston type pump for pumping fluid from the reservoir including a rotatable cylinder block having axial cylinders and pistons reciprocable therein, and means forming an inlet passage for the piston pump opening into the reservoir and adapted to communicate with the cylinders on rotation of the cylinder block,

wherein the annular rim for supporting the annular body of resilient material is arranged to define a chamber substantially isolating air-entrained oil churned by the cylinder block from the intake passage for the piston pump.

Other objects and advantages will become readily apparent from the following detailed description, taken in connection with the accompanying drawings, in which:

Figure 1 is a top plan view of an oil pump embodying my invention;

Figure 2 is a vertical sectional view taken along the line 2-2 of Figure 1; and

- Figure 3 is a schematic view of the various devices incorporated in the oil pump system together with the passages connecting the devices.

While an illustrative embodiment of the invention is the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

Referring now to the drawings, the invention is illustrated in connection with an air blower and oil pump system adapted for use with an oil burner to supply air and metered quantities of fuel oil to an atomizing nozzle 10 associated with the burner. The unit comprises a casing 11 rotatably supporting a drive shaft 12 which may be driven by any suitable means. The drive shaft is connected within the unit to drive (1) an air blower 13 for providing a source of primary atomizing air under pressure for delivery to the nozzle 10, (2) a gear type lift pump 14 for delivering fuel oil from a source of supply, such as a tank, to a cylindrically shaped reservoir 15 formed in the casing 11, and (3) a piston type metering pump 16 for delivering a metered quantity of oil from the reservoir 15 to the nozzle 10 of the burner. Oil delivered from the pump 16 is controlled by a primary-air-operated shutoif valve 17.

Air is admitted to the blower 13 through an intake mufller 21 at the right hand end of the casing 11, and air from the muffler is delivered through a passage 22 (Figure 3) to the intake side of the blower. Air is directed from the blower through an exhaust passage 27, which is in turn connected to the atomizing nozzle 10.

The lift pump 14, which is a conventional gear type pump, is located at one end (the right end as viewed in Figure 2) of the reservoir 15. It includes a small externally toothed gear 30 keyed to the shaft 12 and meshing with an eccentrically mounted internally toothed ring gear 31 having a diameter larger than the gear 30 to provide space for an intervening crescent 32. A fixed outer ring 33 surrounds the ring gear 31 to enclose the gear pump within a recess forming a pumping chamber. An intake passage 34 (Figure 3) for the pump 14 opens into the upper portion of the reservoir 15. The casing is provided with an inlet 36 leading through the cylindrical wall of the reservoir 15 from a fuel oil supply tank (not shown). The reservoir 15 is provided with a cylindrically shaped screen 35 positioned concentrically within the reservoir adjacent the cylindrical wall of the reservoir so that all oil drawn into the pumps from the reservoir is filtered through the screen. The pump 14 creates a reduced pressure in the reservoir 15 which functions to draw oil from the storage tank into the reservoir 15 through the inlet 36 and through the screen 35. The pump 14 serves to maintain a supply of fuel oil in the reservoir 15 for delivery by the metering pump 16 to burner nozzle 10.

The capacity of the pump 14 exceeds the capacity of the pump 16 so that an excess of oil will be pumped into the reservoir by the pump 14. Thus, when the level of oil in the reservoir 15 reaches the inlet passage 34, the excess oil is drawn through the inlet 34 to the pump 14 and is discharged from the pump through an outlet passage 37 having a connection to a T-fitting 38. In single pipe installations, such as that illustrated in the drawings, fuel delivered by the lift pump to the reservoir in excess of the quantity pumped by the metering pump is directed through a passage 39 leading from the T-fitting 38 to a shaft seal 18.

The shaft seal 18 is provided in a recess 42 in the casing 11 between the blower 13 and the lift pump 14 to prevent leakage of fuel oil from the pump 14 along the shaft to the blower 13. Oil is drained from the recess 42 in which the shaft seal is mounted by means of a passage 40 connected to the bottom of the reservoir 15. In two pipe installations, a plug 3811 may be removed from the fitting 38 and a blocking plug threaded into the passage 39 to direct the excess oil through a return passage to the storage tank.

The metering pump 16 includes a cylinder block 50 fixed to the shaft 12 for rotation therewith but slidable axially therealong by means of a splined connection including a pin 51 secured to the block and fitted in a slot formed on the shaft. The cylinder block is providedwith cylinders 53 in each of which a piston 54 is reciprocable. Each piston has an end portion positioned exteriorly of the cylinder which carries a collar 55 fixed thereto. Extending between the collars and the cylinder block and surrounding each of the end portions of the pistons are compression springs 56 which serve to constantly urge the pistons outwardly on their intake strokes and to yieldably hold the end of the cylinder block in sealing engagement with a port plate 65.

A swash plate is provided for moving the pistons 54 on their discharge strokes to pump fuel to the atomizing nozzle. The swash plate is mounted on a removable end plate 58 for the reservoir 15 and comprises a cam block 59 having a face 60 slanted with respect to the axis of the shaft and carrying a bearing pin 61 which rotatably supports a disk-like spin plate 62. Sliding contact is maintained between the face 60 of the cam block and the adjacent face of the spin plate to provide support for the spin plate in a direction axially of the cylinders in the block. The opposite face of the spin plate is provided with a plurality of recesses 63, each adapted to receive a rounded end portion formed on the outer end of the pistons. The cam block 59 which backs up the spin plate 62 is mounted for rotatable adjustment so that it may be adjusted to positions wherein the reciprocation of the pistons 54 will be placed out-of-phase with the pump ports to vary the volume of fluid pumped, as described more fully in my copending application filed on October 25, 1955 as Serial Number 542,685.

The intake for the metering pump includes a passage 64 formed in the port plate 65 located between the pumps 14 and 16. The passage 64 leads from the bottom of the reservoir 15 to an inlet kidney formed in the face of the port plate 65 adjacent the cylinder block 50 and communicating with the pistons on their intake stroke. Discharge from the metering pump is through an outlet kidney formed in the face of the port plate 65 and a port 66 leading from the outlet kidney to a passage 67 which connects the metering pump with the shutoff valve 17. A passage 68 leads from the shutoff valve 17 to supply fuel oil to the burner nozzle 10.

The shutoif valve 17 is consn'uctcd to control the flow of fuel from the metering pump 16 to the atomizing nozzle and to be normally closed so as to prevent such flow until the primary air pressure reaches a predetermined value. Thus, the shutoif valve 17 includes a valve member '71 slidable in a valve sleeve 70 and normally biased to closed position by means of a spring 80 on start up of the unit to block communication between the passages 67 and 68. A passage 86 leading from the air conduit 27 is connected to supply primary air under pressure to the upper side of a diaphragm 75 to move the valve member 71 to open position to connect the passages 67 and 68 only after suflicient speed of the unit has been attained so as to build up primary air pressure in an amount sufiicient to produce proper atomization. During the time that the unit is operated prior to the time that the shutoff valve 17 is opened, the springs 56 encircling the pistons 54 permit the cylinder block 50 to shift axially on the drive shaft away from the port plate 65 so that fluid delivered from within the cylinders may flow into the reservoir, as described more fully in the copending application of Charles B. Wells, filed November 5, 1952, as Serial Number 318,844, now Patent No. 2,766,693.

Air pressure at the nozzle is controlled so as to avoid a build-up of excessive pressure, by means of an air bleed. The air bleed comprises a plurality of slots 87 formed in the interior of the sleeve 70 and communicating at one end with the diaphragm chamber, so that when the pressure of air in the conduit 27, the passageway 86, and the diaphragm chamber reaches a predetermined high 4 value, the valve member 71 will be moved to a position in which a groove 710 in the valve member 71 places the bleed slots 87 in communication with a leakage port 84 in the sleeve 70 so that air is bled through the port 84 and a passage 85 back to the blower 13, as described more fully in my copending application filed September 20, 1955, as Serial No. 535,464, now Patent No. 2,832,403, granted April 29, 1958.

In systems of the type described, pulsations of fluid pumped by the gear type lift pump and vibrations created by the moving parts of the pumping mechanisms are transmitted to fluid in the reservoir and give rise to an objectionable hum or vibration noise which, unless eliminated, may be transmitted to the fuel supply lines and the supply tank and other adjacent structures. An important feature of the present invention is the provision of new and improved means for eliminating the hum or vibration described. This means includes a body of resilient or shock-absorbent material adapted to be disposed in the reservoir so as to have at least a portion immersed in the fluid to absorb the vibrations or pulsations transmitted to the fluid. As seen in Figure 3, the body may be made of porous, i.e. spongy, rubber and in the form of an annular ring arranged relative to the intake passage 34 of the lift pump 14, and consequently the fluid level in the reservoir, so that all but a small portion of the annular ring is immersed in oil and has exposed surfaces in the oil adapted to receive vibrations in the fluid so that the vibrations are absorbed rather than being transmitted through the fuel supply lines to other structures.

The annular ring 90 of shock absorbent material, is supported in the reservoir by means of an annular rim 91 of relatively rigid material about which the annular body 90 is encircled. The body 90 may be removably attached to the rim 91 by stretching the body 90 so that its tensioned condition retains it in place, or it may be semi-permanently attached to the rim by adhesive means. The annular rim 91 is formed with a lip 92 which is adapted to be retained by an annular clamping member 93 of channel-shaped cross section adapted to also receive one end of the cylindrically shaped screen 35. The other end of the screen 35 is positioned against a shoulder 94 formed in the reservoir 15 and the removable end plate 58 engages the annular clamping member to removably hold the assembly of the screen 35, the body 96, the rim 91 and the clamp 93 in place in the reservoir. It will be seen that this arrangement incorporates into one assembly the removable or replaceable parts of the unit so as to facilitate their removal and insertion with a minimum of time and labor.

In devices of the character shown it is desirable that the oil delivered by the metering pump be entirely free of air bubbles which frequently become entrained in the oil contained in the reservoir 15. The arrangement of the intake passage 34 for the lift pump 14 at the top of the reservoir insures that oil pumped by the lift pump in excess of that required by the metering pump is drawn from the top of the reservoir. And since the air bubbles tend to rise in the oil the excess drawn off by the lift pump includes much of the air-entrained oil at the top of the reservoir. Additionally, the location of the intake passage 64 for the metering pump 16 at the bottom of the reservoir further insures that the oil drawn in by the metering pump is free of air bubbles since the bubbles tend to rise. However, the rotation of the cylinder block 50 and the attendant reciprocation of the pistons 55 churns the oil in the reservoir and introduces air bubbles which may find their way to the metering pump intake passage 64. An added feature of the invention includes the formation and location of the annular supporting rim 91 in a manner to function as a baffle which serves to separate the oil churned on rotation of the cylinder block from the intake passage 64 so that only the relatively static oil which is free of air bubbles is drawn into the metering pump. Thus, it will be noted that the rim 91 is of a substantial length and encircles the cylinder block in spaced relation thereto to provide a cham' her in which the churned oil is substantially retained and separated from the intake passage 64.

I claim:

1. A hydraulic pumping mechanism comprising, a cas ing having a reservoir formed therein for hydraulic fluid, an inlet in the casing for admitting fluid to the reservoir, a drive shaft mounted in the casing having a portion extending into the reservoir, a gear pump located at one end of the reservoir and connected to be driven by the drive shaft for drawing fluid into the reservoir, a piston pump located in the reservoir to pump fluid from the reservoir including acylinder block mounted on the drive shaft for rotation therewith, said cylinder block having a plurality of axial cylinders and pistons reciprocable therein, a port plate located in the reservoir between the gear pump and the piston pump, said port plate having an intake passage for the piston pump including a portion opening into the reservoir at a position disposed radially outwardly of the cylinder block and a portion adapted to communicate with the cylinders on rotation of the cylinder block, an annular body of resilient material located in the reservoir and spaced from the walls of the reservoir for absorbing vibrations transmitted to the fluid by said pumps, an annular rim of relatively rigid material surrounding the cylinder block in spaced relation thereto for supporting the annular body of resilient material, said rim being disposed radially inwardly of the portion of said intake passage opening into the reservoir so that the rim functions as a bafiie to separate fluid churned on rotation of the cylinder block from the intake passage for the piston pump,- and means for releasably retaining the annular rim in place in the reser von.

2. A hydraulic pumping device comprising, a casing having a cylindrical reservoir formed therein for hydraulic fluid, an inlet in the casing for admitting fluid to the reservoir through the cylindrical wall thereof, pumping mechanism located within the reservoir including a piston pump comprising a rotatable cylinder block having a plurality of axial cylinders with pistons reciprocable therein, means forming an intake passage for the piston pump opening into the reservoir radially outwardly beyond the cylinder block and adapted to communicate with the cylinders on rotation of the cylinder block, an annular rim of relatively rigid material surrounding the cylinder block in spaced relation thereto, said rim being disposed radially inwardly of the intake passage opening into the reservoir to function as a baffle to separate fluid churned on rotation of the cylinder block from the intake passage, an annular body of shock absorbent material encircling the rim and supported thereon so as to be substantially immersed in fluid in the reservoir to absorb pulsations transmitted to the fluid from the pumping mechanism, a cylindrical screen encircling said annular body of shock absorbent material and said pumping mechanism so that all fluid reaching the pumping mechanism is filtered through the screen, one end of the cylindrical screen being positioned against one end of the cylindrical reservoir, an annular clamping ring at the other end of the cylindrical screen for holding the screen and said annular rim, and a removable end plate form ing a part of said casing engaging said annular clamping ring for retaining the assembled rim, shock absorbent material, screen and clamping ring in place in the reservoir.

3. A hydraulic pumping device comprising, a casing having a cylindrical reservoir formed therein for hydraulic fluid, said casing having an inlet on the periphery of the reservoir for admitting fluid to the reservoir, pumping mechanism located within the reservoir including a piston pump comprising a rotatable cylinder block having'a plurality of axial cylinders with pistons reciprocable therein, means forming an intake passage for the piston pump opening into the reservoir radially outwardly beyond the cylinder block and adapted to communicate with the cylinders on rotation of the cylinder block, an annular rim of relatively rigid material surrounding the cylinder block in spaced relation thereto, said rim being disposed radially inwardly of the intake passage opening into the reservoir to function as a baflle to separate fluid churned on rotation of the cylinder block from the intake passage, a cylindrical screen encircling said annular rim and said pumping mechanism so that all fluid reaching the pumping mechanism is filtered through the screen, one end of the screen being positioned against abutment means in the reservoir, an annular clamping ring at the other end of the cylindrical screen having a generally U-shaped cross section embracing said other end of the screen and one end of said annular rim for holding the screen and mm in assembled relationship, and a removable end plate forming a part of said casing and engaging said clamping ring for retaining the assembled rim, screen, and ring in place in the reservoir.

4. A screen and vibration damper assembly for use in a fluid pump comprising, an annular rim having a lip of greater diameter than the rim, an annular ring of shock absorbent material seated on the rim, a cylindrical screen having an inner diameter approximating the outer diameter of the lip, said screen encircling the lip and ring, and a clamp engaging the screen and the lip to hold the screen and rim in assembled relationship.

5. A screen and vibration damper assembly for use in a fluid pump having a reservoir comprising, an annular rim having a lip of greater diameter than the rim, an annular ring of shock absorbent material seated on the rim, a cylindrical screen having a diameter slightly less than the diameter of the reservoir and greater than the diameter of the lip, and a U-shaped clamp having one leg engaging the screen and the other leg engaging the lip to hold the rim and screen in assembled concentric relationship.

References Cited in the file of this patent UNITED STATES PATENTS 594,039 Serve Nov. 23, 1897 2,311,916 Wahlmark Feb. 23, 1943 2,316,007 Lockett Apr. 6, 1943 2,448,118 Pellettere Aug. 31, 1948 2,460,649 Muller Feb. 1, 1949 2,766,693 Wells Oct. 16, 1956 

